In electrical circuits, particularly in the low-voltage range, in the case of noise-sensitive lines in communication engineering and information technology and in the case of sensitive electronic components, it is possible to use protective components. These can be used to render inadmissibly high currents or voltages harmless and to discharge them to ground or to convert them into heat energy. This allows the components to be protected from inadmissible heating, which can at least cause a fault in component operation, and, in the extreme case, from destruction.
Various types of protective components are known which can be used according to the desired operation and, if appropriate, can also be combined with one another. To protect against excessive currents and voltages, it is possible to use arrestors, thermistors or varistors, for example.
Normally, protective components are used as separate components and are soldered on boards, for example. In this context, however, each soldered component requires a provided electrical leakage path, for which it is necessary to observe a certain clearance from the adjacent component. Boards to which components are fitted automatically also require a certain clearance between individual components so that the component fitting machine can set down the component with certainty or possibly grip it again too. This results in a high space requirement overall on boards which goes beyond the sum of the component dimensions themselves. Not least for this reason, attempts are therefore often made to combine different component functions on modules, specifically on the one hand to improve performance but on the other hand to save space on the board.